| F | SK | MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING |
| F21 | USK | LIGHTING; HEATING |
| F21 | KL | LIGHTING (electric aspects or elements, see section H, e.g. electric light sources H01J , H01K , H05B) |
| F21Y | UKL | INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21L , F21S and F21V , RELATING TO THE FORM OF THE LIGHT SOURCES [7] |
| F21Y 101/00 | HGR | Point-like light sources [7] |
| F21Y 101/02 | UGR1 | | . | Miniature, e.g. light emitting diodes (LED) [7] |
|
| F21Y 103/00 | HGR | Elongated light sources, e.g. fluorescent tubes [7] |
| F21Y 103/02 | UGR1 | | . | curved, e.g. ring-shaped [7] |
|
| F21Y 103/025 | UGR2 | |
| F21Y 105/00 | HGR | Planar light sources [7] |
| F21Y 111/00 | HGR | Light sources of form not covered by preceding groups [7] |
| F21Y 113/00 | HGR | Combination of light sources [7] |
| F21Y 113/02 | UGR1 | |